What caliper to buy

[ledpen]

I'm trying to purchase some upgraded calipers for the front of my 1.2 merit as I will be fitting a c20xe at some point, I know the most common discs to use is 24 by 256mm, but what car do the calipers come off? I've been searching on ebay for calipers but I'm really unsure what I'm actually meant to be looking for, some help or advise would be great

[mowgli]

calibre, astra gsi, cavalier gsi, early Vectra. they were fitted to loads really

[Jack]

Usually referred to as 'ATE' calipers. Off the top of my head I can't remember what the caliper casting marks are for the ones that take 256mm discs though

[ledpen]

Would anyone happen to have a part number?